Portable apparatus for the non-destructive measurement to the internal quality of vegetable products

ABSTRACT

Instrument for measuring the properties of vegetable products, comprising:—an energy source adapted to direct a radiation against the fruit,—means for picking up the radiation being re-emitted by said fruit,—a spectrograph analysing said radiation,—means for conveying said radiation into the spectrograph,—means for processing the data generated by the spectrograph, in which the energy source comprises a plurality of LEDs contained in a single portable casing provided with a handgrip and a probing head. The spectrograph and the processing means are physically separated from said portable casing, to which they are electrically and optically connected via at least a multiple optical/electric connection. The LEDs are provided in closed-loop arrangements on the surface of the probing head and said means for picking up the re-emitted radiation are arranged at the centre of the rings formed by the LEDs that emit radiations whose respective emission spectra are contiguous.

[0001] The present invention refers to a portable apparatus for the measurement of the value of some internal substances and properties of vegetable products, in particular individual items of any fruit variety whatsoever, said internal substances and properties being adapted to be indicative of, ie. reveal the internal “quality” of the fruit being measured.

[0002] Fruit is largely known to be usually picked off and then selected, ie. graded through a process that is based on a variety of judgements, inspections and examinations, as far as not only the correct time for picking off, which should ideally occur when the characteristics of the products to be picked off are at an optimum altogether, but also the kind of inspections and controls are concerned, which must be carried out on the most significant properties of each single fruit item in order to evaluate the most important characteristics in view of grading the quality and, therefore, determining the final commercial destination thereof.

[0003] However, since the ideal time for picking off the fruit can most obviously be only identified when the fruit is actually still ripening and, therefore, still on the tree (being it actually possible, but quite risky to pick off fruit and examine it only afterwards to find out that it has been picked too early), the need arises, for a correct selection of the most favourable time for picking off, for said inspections and controls to be able to be carried out on the fruit items before picking them off, ie. when they are still on the tree.

[0004] However, since vegetable products are natural products, they possess characteristics that may be non-uniform, ie. may change from a piece of fruit to the next one, and this fact does not enable the quality and the ripening state of each single fruit item to be merely assessed on the basis of a simple sample test to be carried out on a limited number of fruit items that have been previously picked off the tree.

[0005] Furthermore, an assessment of the ripening state of fruit depends on a number of parameters, such as mainly the sugar contents, acidity, water contents and hardness. However, the factor that actually makes it particularly difficult for a suitable instrument to be implemented and a single procedure to be adopted for measuring the degree of ripening of the vegetable products, is that each single species thereof has its own peculiar characteristics of the ripe product, which may often be also quite different from the similar characteristics of an equally ripe product that belongs to a different species. All this is anyway well known to all those skilled in the art, so that it shall not be dealt with here any further, in the same way as the large number of examples that can be given here in this connection shall be omitted for reasons of greater simplicity.

[0006] It is therefore an obvious and easily understandable fact that the search for a measurement apparatus and related procedure for measuring the degree of ripeness in general of vegetable products has split up into a rather high number of technical solutions in connection with both the variety of technical investigation means used (such as, for example, laser beams, quartz-iodine or halogen light, advanced statistical processing methods) and the concepts of implementation of specialized measurement apparatuses/instruments for each single species of vegetable products to be measured.

[0007] In general, the state of the art in the field of not only the measurement of some significant properties of vegetable products both during and after picking off, but also the methods of processing the data issuing from these measurements and the related measuring and processing apparatuses/instruments is collected in the bibliography listed in the enclosed Table 1 (sections A and B).

[0008] A number of instruments and apparatuses are therefore largely known in the art for measuring in an automatic and relatively low-cost manner the value of some of the above cited parameters; to mere documentary evidence purposes following references may be cited in this connection: EP 957353, U.S. Pat. No. 4,473,292, U.S. Pat. No. 5,844,678, U.S. Pat. No. 5,658,798, U.S. Pat. No. 5,708,271. The latter refers in particular to the sole control of the Brix degree as performed with a non-portable apparatus.

[0009] However, all these apparatuses or instruments are industrial means intended for application in the mass processing of fruit items that have already been picked off the tree, or else are laboratory-scale apparatuses, so that none of them is actually adapted, nor likely to be capable of being adapted, to be used as a portable instrument for testing fruit pieces as they are still hanging on the tree.

[0010] The U.S. Pat. No. 5,519,219 discloses an apparatus for the spectrometric measurement and the quantitative identification of solids, liquids and gases, comprising an IR source and a LED-based reading device. This apparatus, however, can examine both solids and liquids or gases, so that it is absolutely not suitable for use to solely measure such special items as individual pieces of fruit.

[0011] The patent publications JP 10206323, JP 10160670, JP 08068751, JP 081288949 disclose technical solutions for the analysis of properties of vegetable products through the utilization of laser ray beams; however, such a technology is quite delicate, expensive and does not lend itself to any agile utilization for the assessment of the qualities of vegetable products that are still hanging on the tree, ie. have not been picked off yet.

[0012] The patent publication WO 00/02036 refers to a non-portable instrument that has anyway been conceived to solely analyse the chlorophyll contents in a vegetable product; such a solution is quite obviously capable of generating an information of a considerably limited extent that cannot therefore be reasonably relied upon as far as an assessment of the degree of ripeness of the examined product is concerned.

[0013] The patent publication U.S. Pat. No. 5,822,068 covers the analysis of vegetable products to be only performed, through the examination of luminescence, after that such products have been picked off, actually. To such a purpose, use is made of both low-intensity and high-intensity red light beams and this causes such a method to become rather complex and expensive and, therefore, practically unfitted to applications involving controls to be carried out in a quick and throughout reliable manner.

[0014] The patent publication EP 0939316 discloses a method and an apparatus for the measurement of the internal characteristics of a fruit item. However, the therein disclosed solutions have a major drawback in that they make use of a traditional light source, which therefore is very expensive from an energy usage viewpoint and, as a result, practically non-portable. In addition, the suggested solution provides for a bundle of optical fibres carrying the radiation to be placed in contact with the same portion of the fruit surface along with another bundle of optical fibres carrying the feedback, ie. return radiation. It has however been found that such a solution has a major drawback in that the feedback radiation that is picked up in this way is very low in level and, furthermore, is markedly contaminated by the effect of direct reflection, by the surface of the fruit, of the incident radiation. As a result, the radiation that is so obtained in return from the fruit is rather disguised and scarcely capable of being decoded into simple and reliable pieces of information.

[0015] Finally, what is actually processed in this case, and hence the results that are so worked out, are based on an average of all measurements that are carried out, and not on the measurements of each single product, so that they are not fitted for use in view of a punctual evaluation of each product; alternatively, the evaluation of a single product requires two distinct measurements to be carried out, so that it turns out to be quite demanding and complex in operational terms and, therefore, all the more so scarcely usable in applications involving measurements on products that have not yet been picked off.

[0016] Known from the disclosure in U.S. Pat. No. 5,324,945 is a method for the non-destructive measurement of the sugar contents of fruit items; this method, however, is based on a non-portable apparatus and, furthermore, is limited to the sole measurement of the sugar contents.

[0017] It therefore is desirable, and is actually a main purpose of the present invention to provide a technical solution, and a related instrument, for the non-destructive measurement of some internal substances and properties of a vegetable product, in which said instrument shall further be capable to be conveniently used on fruit items that are still hanging on the tree, ie. have still to be picked off; it shall be conveniently portable and be capable of generating electric signals that are adapted to be appropriately processed so as to provide information that is capable of being correlated with the state of ripeness and the quality of the fruit being examined.

[0018] According to the present invention, this aim, along with other features of the present invention, is reached in a portable apparatus that is made and operates as recited in the appended claims.

[0019] Anyway, features and advantages of the present invention will be more readily understood from the description that is given below by way of non-limiting example with reference to the accompanying drawings, in which:

[0020]FIG. 1 is a schematic and symbolical view of the two assemblies that constitute an instrument according to the present invention;

[0021]FIG. 2 and FIG. 3 are a top view and a front view, respectively, of the left-hand assembly of FIG. 1;

[0022]FIG. 4 is a symbolical, schematic view of the connections between the main functional members of the instrument according to the present invention;

[0023]FIG. 5 is a diagrammatical view of an example of the light radiation intensity as a function of the wavelength of an either traditional or halogen light source;

[0024]FIG. 6 is a diagrammatical view of a plurality of curves relating to the light radiation intensity as a function of the wavelength of respective LEDs selected according to the present invention;

[0025]FIG. 7 is an enlarged front view of the portion identified as “C” in FIG. 3;

[0026]FIG. 8 is a view of the same portion according, to the section A-A in FIG. 7;

[0027]FIG. 9 is an enlarged view of the terminal portion of the left-hand assembly of FIG. 1;

[0028]FIG. 10 is a view of a component part of said terminal portion, as seen according to the section B-B in FIG. 9;

[0029]FIG. 11 is an enlarged view of part of the display provided on the right-hand assembly of FIG. 1;

[0030]FIGS. 12 and 13 are the same view as the one shown in FIG. 9, with the addition of variously sized vegetable products as arranged in the respective measurement positions relative to the measuring instrument according to the present invention.

[0031] With particular reference to FIG. 1, it can be noticed that an instrument according to an example of embodiment of the present invention comprises:

[0032] a portable structure, preferably in the shape of a handgun and anyway provided with a handgrip 1 and a probing head 2;

[0033] a spectrometer 3 associated to suitable processing and computing means 4, which are preferably given the same architecture as a personal computer (PC); said spectrometer 3 and said processing and computing means 4 are preferably assembled and integrated inside a single casing 21, which is also portable, so as to ensure full portability of the entire instrument;

[0034] a plurality of electric and optical connections, twisted and joined together into a single cable 5, provided between said handgrip 1 and the association between said spectrometer 3 and said PC 4.

[0035] Some basic teachings of the present invention need at this point to be introduced; according to the prior art, instruments and apparatuses are disclosed, which generate and emit a light or quasi-light radiation (NIR, Near Infrared Radiation) having a quite wide spectrum (see FIG. 5), ie. a spectrum that is therefore the ideal one in view of being able to analyse the properties and the quality of the inner part of vegetable products; however, these apparatuses make use of a light source that comprises either a halogen, ie. quartz-iodine lamp or a traditional lamp. In other words they use illuminating means that use a lot of energy.

[0036] On the other hand, since it is desired that such means be capable of being portable, the absolute need arises for these means to be provided with portable energy sources, ie. batteries. Owing to these means implying a rather large energy usage, as stressed above, it would however prove necessary to either make use of quite heavy and bulky power-supply batteries, and this would of course affect the actual transportability of the apparatus, or drastically limit the operating endurance, or self-sufficiency and this would of course imply a significant reduction in the actual usefulness and the advantages in the use of the apparatus.

[0037] In order to do away with such drawbacks, the use is therefore proposed of light sources based on the use of LEDs (ie. Light Emitting Diodes), which have a very low energy usage and, as a result, are capable of being supplied for a long period of time from light-weight and compact-sized batteries.

[0038] Said probing head 2 of the apparatus according to the present invention comprises:

[0039] a plurality of LED devices 6 arranged on the end portion of said probing head;

[0040] a pick-up member 7, arranged in close proximity of said LEDs 6 to pick-up light from outside,

[0041] one or more optical fibres 8, connected to said light pick-up member 7 on one side and, on the other side, to said spectrometer 3.

[0042] Quite logically, there are furthermore provided, although not shown in the Figure, the circuits that are required to ensure the power supply to said LED devices 6.

[0043]FIG. 4 illustrates a symbolical, simplified block diagram showing the various component parts of the apparatus according to the present invention, which will be used further on in this description and are useful in view of better understanding the real object of the invention.

[0044] However, each type of said LEDs is capable of emitting light on a very narrow spectrum, in particular a spectrum that is much narrower than a halogen light spectrum.

[0045] Such a circumstance gives rise to a severe limitation, since the reliability and accuracy of the spectrum analysis of the return or feedback radiation depends to a quite large extent on the amplitude of the spectrum itself.

[0046] In order to remove such a limitation, a plurality of LEDs are actually selected, which have respective differentiated, but substantially contiguous spectra 9, so that in their entirety they are capable of generating a light radiation having an overall spectrum that is approximately as wide as the spectrum 9A of a halogen or traditional light source (see FIG. 6).

[0047] A light radiation is in this way obtained, which has approximately the same characteristics as a halogen light radiation, while however implying an extremely reduced low-voltage energy usage that can therefore be quite well sustained by normal general-purpose portable batteries.

[0048] In an advantageous manner, in view of enabling the so obtained light radiation to uniformly penetrate the item to be examined, as well as the light radiation re-emitted outside from the item to be picked up in a manner that is not distorted by the geometry of both the transmission and pick-up means, said LEDs and said light pick-up member 7 are arranged coaxially, and preferably, with reference to FIGS. 7 and 8, said LEDs are arranged according to one or more closed-loop ring patterns, while said light pick-up member 7 is arranged at the centre of such closed-loop ring patterns.

[0049] Said light pick-up member is constituted by the outer surface 10 of the termination of the optical fiber 8.

[0050] The mode of operation of this part of the instrument according to the present invention is as follows: the probing head 2 is first of all approached to the vegetable product so as to enable the pick-up member 7 to come into a soft contact with the surface of the product to be analysed; then, the previously energized LEDs emit a corresponding radiation that strikes upon the surface of the product and penetrates the product itself.

[0051] The behaviour of such a radiation is well-known; a part of this radiation in the visible and NIR spectrometric region (400 nm-2500 nm) is refracted and scattered into the body of the product from the sub-epidermal layers of the vegetable product, and then returns towards the surface of the product and, moving beyond the barrier constituted by the peel, gets back to the outside. In particular, the chemical bonds of a determined substance absorb the energy associated to specific wavelengths in proportion to the concentration of that substance. The possibility is therefore given for the concentration of the substance to be determined through the measurement of the absorption.

[0052] A part of the radiation that moves beyond the peel, and so gets back to the outside of the product (return or feedback radiation), is picked up by said pick-up member 7 by means of one or more optical fibres 8, which transmit the so received radiation to an appropriate spectrometer for further processing, as this shall be described in greater detail further on.

[0053] In order to ensure that said return radiation is not likely to be mixed either with the ambient light or the radiation being directly emitted by said LEDs, and therefore reaching by diffusion also said pick-up member, with reference to FIG. 8 following geometry is selected:

[0054] the LEDs 6 are arranged according to a closed-loop ring pattern, and oriented outwards, on the surface of said probing head;

[0055] at the centre of said closed-loop ring there is arranged said pick-up member 7, which is internally connected with one or more optical fibres 8 and terminates externally with a pick-up surface 10; an internally hollow cylinder 11, preferably of an elastomeric or, anyway, similar soft material, is provided between said member 7 and said LEDs 6 and is arranged so as to be slightly projecting with respect to both said member and said LEDs, which therefore are set back with respect thereto and, in particular, are not exposed to view among each other, ie. are not visible from each other.

[0056] It will therefore be readily appreciated that, when the head 2 is approached to the fruit, a kind of “obscure chamber”, or “camera obscura”, is created between the same fruit and the pick-up member 7, owing to said hollow cylinder 11 being brought to softly rest against the surface of the fruit; in this way, the pick-up member 7 can be reached solely by the radiation that comes out of the peel and, therefore, is exactly and accurately representative of the internal state of the fruit, since both the ambient light and the light emitted by the LEDs are effectively intercepted and fully barred by said hollow cylinder 11.

[0057] Advantageously, said hollow cylinder 11 may be accompanied, on its outer circular surface oriented towards the fruit, by a particularly soft terminal ring 11A that is capable of being brought to most softly abut against the fruit (see FIG. 7). As an alternative thereto, said terminal ring 11A may be provided directly on said probing head 22 with the aid of proper means, while thereby avoiding to apply said hollow cylinder 11, provided of course that the basic condition is anyway is duly preserved, ie. that the pick-up member 7 is capable of being only and solely reached by the radiation coming from the peel of the fruit and, therefore, from the inner part of the product being measured.

[0058] The radiation that is in this way received by the pick-up member is then sent to the spectrometer, which outputs a graph or a function of the intensity pattern of the return or feedback radiation as a function of the frequency of the same radiation.

[0059] The function supplied by the spectrometer is then processed by the PC according to following criteria:

[0060] for each type of programme selected, there are associated and filed, ie. stored also a multiplicity of formulae and/or algorithms that use the frequencies and the related amplitudes as variables; each formula or algorithm generates a calculation relating to one of the following parameters:

[0061] sugar contents (Brix degree)

[0062] hardness

[0063] degree of ripeness

[0064] acidity

[0065] residual pesticides;

[0066] since in the case described here as an example there are five of said parameters, also said formulae or algorithms will be in the number of five;

[0067] the PC unit processes and solves the formula on the basis of the amplitude of the return radiation at a certain pre-defined number of frequencies of the spectrum, and carries out a processing operation for all formulae associated with the selected programme, thereby obtaining values relating to each one of the above mentioned parameters;

[0068] on the basis of said values obtained by processing out said formulae, the PC unit then outputs an information containing said values it has so just computed.

[0069] In a suitable manner, such an output information of the values that have been processed out on the basis of the measurement (“pre-set” values) occurs in the form of a contemporaneous numerical presentation on a proper display 24; in addition, the maximum and minimum values found from an initial, pre-set measurement, or preestablished quality indexes, may also be detected, recognized and stored, and these values may then be presented on a special display 14A (see FIG. 11) for a final evaluation of the overall peculiarities of a whole lot of vegetable products that have been so analysed.

[0070] It can therefore be readily appreciated that, once the kind of vegetable product to be examined has been identified and the corresponding programme has been selected through proper controls on the keyboard of the PC, the measurement of the characteristics takes place occurs in a very simple, immediate and, above all, fully automatic manner.

[0071] It will also be readily appreciated that the PC unit shall first be loaded with a plurality of computational programmes, corresponding to the various species and conditions of the vegetable products to be analysed, which must be capable of being selectively selected by the operator.

[0072] As far as the determination of said formulae or algorithms, these are obtained by going through a large number of experiments, ie. measurements of the graphs generated by the spectrometer and comparisons with the values of the cited parameters as measured in a conventional, known manner, including the contents and the kind of pesticides that may possibly be present and investigated, ie. checked for. The results of such comparisons are processed with the most appropriate statistical techniques, such as typically multiple regression, designing of fractional factorial experiments, as well as other suitable statistical methods that, however, are not a part of the present invention and shall therefore not be dealt with here any further. Anyway, the outcome of all these processing steps enables the formula or algorithm to be identified, which provides with an adequate, acceptable accuracy the means for determining, or pre-establishing, the value of a definite parameter that is representative of a corresponding characteristic of the internal quality of the fruit, on the basis of the function worked out, ie. found by the spectrometer.

[0073] In an advantageous manner, said spectrometer 3 and said computation means 4 are associated with each other in a single and same assembly, as this is shown in FIG. 1. Associated to such an assembly there are arranged also appropriate peripheral units, such as at least a driver 13 for entering and retrieving data and programmes, a display 14 for the presentation of values of the computed parameters, a printer 13.1 and a keyboard 15 for entering commands.

[0074] However, it is a largely known fact that the value of the parameters that can be detected or found out with known, conventional techniques is markedly dependant on the temperature of the vegetable product being analysed; for this reason, when used in the determination of said formulae/algorithms, said reference values that are so found experimentally should be adjusted with the help of appropriate correction coefficients relating to the temperature of the vegetable product. However, since these experiments are carried out at any prevailing ambient temperature, said corrections, which must be made in order to take into due account the actual temperature of the vegetable product to be analysed, are introduced through an appropriate additional processing step of said formulae/algorithms.

[0075] The need therefore arises for the temperature of the vegetable product to be detected and the result of such a measurement to be suitably entered in said PC unit, so as to be able to work out the computational steps relating to the various parameters in such a way as to duly take such a temperature effect into due account.

[0076] To this purpose, the probing head 2 is provided with a temperature-detection piece 14, as best shown in FIGS. 1, 9, 12 and 13; such a temperature-detection piece comprises in its interior a heat sensor 15 that is sensitive to the IR radiations and is so arranged as to face outwardly, in particular so as to be directed towards the zone lying in front of said probing head 2. The way in which this temperature-detection piece operates can at this point be readily understood; for the vegetable product to be measured, the product itself must be arranged in front of and in contact with said probing head 2, in such a manner as to be able to receive and re-emit the radiation that is emitted by said LEDs, as described above.

[0077] In such a position, the product finds itself in the ideal situation in view of the outer temperature thereof being able to be detected automatically by said heat sensor 15, which is situated in direct view thereof. The so detected temperature value is then sent by said sensor to said PC unit for further processing, as described above.

[0078] In connection with this temperature-detection piece 14, a further improvement thereof appears to be anyway quite desirable; since the vegetable products to be analysed may be of species that differ to also quite large an extent from each other, thereby possibly implying also largely differing sizes, said temperature-detection piece 14, if provided in a fixed position, could give rise to a twofold kind of a drawback. Namely, a first drawback would derive from the fact that said temperature-detection piece 14 might well interfere with said undersized vegetable products, thereby preventing them from being able to be positioned directly in front of and in contact with said LEDs and in front of the outer surface 10 of said optical fiber, and this would clearly affect the accuracy of the measurements to be performed; a second drawback would on the other hand derive from the fact that said heat sensor 15, owing exactly to the fixedness of its position regardless of the size of the vegetable product, would of course find itself positioned each time at very differing distances from the peel of the product, so that the so detected temperature shows and generates absolutely non-allowable margins of error.

[0079] In view of doing away with such a major drawback, said temperature-detection piece 14 is therefore applied in an adjustable manner on the outer edge of said probing head 2 and, in particular, is connected pivotally on the outer edge 16 of said head 2 by pin-assisted hinging, ie. by means of a hinging pin 17, as this is best shown in FIGS. 12 and 13 illustrating the self-adapting property of said temperature-detection piece 14 in accordance with the varying sizes of the vegetable products to be measured.

[0080] Furthermore, in order to enable the operations for the analysis of the properties of the vegetable products to be performed in as quick and convenient manner as possible, it is advantageous that, upon the energization of the LEDs, the phases of activation of the spectrometer, detection of the return or feedback radiation, processing of the obtained values, presentation of the processed values and possible further statistical processing steps, as well as activation of possibly provided peripheral equipment, are switched on through a single activation switch 18, and that such a switch 18 is located in an expedient position on said handgrip 1.

[0081] Finally, in order to ensure full transportability of the measuring instrument, it is advantageous for the spectroscope, the processing and computation means, as well as the remaining peripheral equipment to be integrated into a single casing 26 that is suitable equipped in view of being able to be conveniently transported by a single operator, so as shown in FIG. 1. 

1. Apparatus for the non-destructive measurement of a plurality of internal properties of vegetable products, in particular individual fruit items, comprising: a source of preferably light energy, adapted to direct a radiation towards and through the surface of a vegetable product, pick-up means adapted to pick up the radiation that is re-emitted by said product when it is hit by the energy from said source, a spectrograph (3) for the analysis of the return radiation re-emitted by said item of vegetable product being analysed, means (8) for conveying said radiation to said spectrograph, means (4) for processing and computing the spectrum frequency and amplitude data produced by said spectrograph, characterized in that: said light energy source comprises a plurality of LEDs (6), said LEDs, as well as said means provided to pick up said return light radiation, are contained in a single portable casing provided with a handgrip (1) and a probing head (2) adapted to be brought into close proximity of or in contact with the product to be measured, said spectrograph (3) and said processing and computation means (4) are physically separated from said portable casing (1, 2), to which they are connected electrically via at least an electric connection (5).
 2. Apparatus according to claim 1, characterized in that said means for conveying said return light radiation to said spectrograph are at least partially contained in said handgrip (1) and said probing head (2).
 3. Apparatus according to claim 2, characterized in that said LEDs (6) are arranged according to a closed-loop ring pattern on the prominent surface of said probing head (2), and said pick-up means (7) for picking up the radiation re-emitted by the product are arranged substantially at the centre of said ring formed by said LEDs.
 4. Apparatus according to claim 3, characterized in that said pick-up means are constituted by the termination 10 of at least an optical fibre
 8. 5. Apparatus according to any of the preceding claims, characterized in that said LEDs emit respective radiations, the corresponding emission spectra (9) of which are substantially contiguous.
 6. Apparatus according to any of the preceding claims, characterized in that between said LEDs, and said pick-up means there is provided a hollow cylinder (11) which prevents the radiation emitted by said LEDs from directly reaching said pick-up means, said hollow cylinder being possibly coupled to or replaced by a terminal ring (11A) adapted to be brought into abutting against said vegetable product.
 7. Apparatus according to claim 6, characterized in that said shielding device projects from said probing head (2) beyond the terminal borders od said LEDs and said pick-up means (7).
 8. Apparatus according to any of the preceding claims, characterized in that on the edge (16) of said probing head (2) there is arranged a temperature-detection piece (14) provided with a heat sensor (15).
 9. Apparatus according to claim 9, characterized in that said temperature-detection piece (14) is provided pivotally with respect to said probing head (2) by means of a hinging pin (17) that is firmly joined with said head (2).
 10. Apparatus according to any of the preceding claims, characterized in that the activation of said spectrograph (3) and said processing and computation means (4) is adapted to be triggered by a single activation switch (18).
 11. Apparatus according to claim 10, characterized in that said activation switch (18) is arranged on said handgrip (1).
 12. Apparatus according to any of the preceding claims, characterized in that said spectrograph and said processing and computation means (4) are assembled and integrated into a single portable casing (26).
 13. Apparatus according to claim 12, characterized in that said processing and computation means are adapted to go through previously programmed algorithms, and solve previously programmed formulae, on the basis of the quantities, ie, values detected by said spectrograph and previously entered constants, so as to obtain a plurality of values, each one of which is correlated in a univocal manner with at least one of the following parameters: sugar contents (Brix degree) hardness degree of ripeness acidity residual pesticides.
 14. Apparatus according to claim 13, characterized in that said processing and computation means comprise a visualization display (24) adapted to display a combination whatsoever of one or more of the afore cited parameters.
 15. Apparatus according to claim 13 or 14, characterized in that said visualization display (24) is provided with a specially intended field (display 14A) adapted to display the outcome of the statistical processing of a plurality of measurements performed in connection with one or more of said parameters.
 16. Apparatus according to one or more of the preceding claims, characterized in that said processing and computation means (4) are provided with peripheral equipment comprising at least a disk-drive unit (13) and a printer (13,1). 